JP2012102848A - Hydraulic control device of automatic transmission - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hydraulic control device, which is capable of performing closure control of hydraulic pressure with an automatic transmission using an accumulator as a hydraulic source, and which avoids an excessive hydraulic pressure from being applied from the accumulator when power is shut off.SOLUTION: The device includes a normally open solenoid valve for supplying the hydraulic pressure of the accumulator to a hydraulic chamber or the like of a continuously variable transmission, and a normally close type solenoid valve for exhausting a pressure from the accumulator. In the device, when an operation of shutting off the power to these solenoid valves is performed (step S1), each solenoid valve is controlled to an open valve state (step S2) and the hydraulic pressure is reduced by exhausting the pressure from the accumulator. After the hydraulic pressure of the accumulator is lowered to a predetermined value (step S3), the power to the solenoid valve is stopped (step S4), and the supplying solenoid valve is controlled to an open state and the pressure exhausting solenoid valve is controlled to a close state.

Description

  The present invention relates to a control device for an automatic transmission for switching a gear ratio and a forward / reverse state in a vehicle, and more particularly to an apparatus for controlling a hydraulic pressure for setting a gear ratio and switching a forward / reverse state. It is.

  BACKGROUND ART An automatic transmission for a vehicle is configured to electrically control a torque transmission state in a power transmission system from a driving force source such as an engine to a driving wheel in accordance with a vehicle state such as a vehicle speed and a required driving amount. ing. Specifically, the line pressure is adjusted according to the torque that should be transmitted by electrically changing the pressure regulation level of the line pressure according to the vehicle speed, accelerator opening, etc., and the control valve is electrically controlled. By doing so, the hydraulic pressure for the actuator for setting the gear ratio is controlled.

  The hydraulic pressure for performing such control is generated by driving an oil pump with an engine or an electric motor in a vehicle, and in recent years, securing the hydraulic pressure when stopping the engine when temporarily stopped, Alternatively, an accumulator is provided to store the hydraulic pressure generated by regenerative energy. Patent Document 1 discloses a hydraulic control device for a belt-type continuously variable transmission, which includes an accumulator in parallel with an oil pump driven by a motor. The belt type continuously variable transmission includes a driving pulley (hereinafter referred to as a primary pulley) to which torque is input from a driving force source such as an engine, and a driven pulley (hereinafter referred to as a secondary pulley) coupled to an output shaft. Further, the hydraulic control device includes an electric oil pump and an accumulator as a hydraulic source, and the hydraulic pressure generated by the hydraulic source is supplied to a primary pulley that controls the gear ratio. It has a first supply valve for supplying to the hydraulic chamber and a second supply valve for supplying to the hydraulic chamber in the secondary pulley that controls the transmission torque in accordance with the clamping pressure for clamping the belt. Also, a first discharge valve that discharges pressure oil from the hydraulic chamber in the primary pulley and a second discharge valve that discharges hydraulic pressure from the hydraulic chamber in the secondary pulley are provided. These supply valves and discharge valves are constituted by electrically controlled valves such as solenoid on-off valves.

  In the belt-type continuously variable transmission described in Patent Document 1, the first supply valve is opened to supply the hydraulic pressure of the hydraulic source to the hydraulic chamber in the primary pulley, or the first discharge valve is opened. The gear ratio is controlled by discharging the hydraulic pressure in the hydraulic chamber of the primary pulley. On the other hand, when the second supply valve is opened and hydraulic pressure is supplied to the hydraulic chamber in the secondary pulley, or when the second discharge valve is opened and hydraulic pressure in the hydraulic chamber in the secondary pulley is discharged, the belt The transmission pressure capacity is controlled by changing the clamping pressure.

  Japanese Patent Laid-Open No. 2004-228561 uses a hydraulic oil stored in an accumulator for control of a belt-type continuously variable transmission, while lubricating oil for lubricating parts of a clutch, a torque converter, or an automatic transmission that transmits driving torque. A hydraulic control device configured to be used in is described. Also in the hydraulic control apparatus described in Patent Document 2, the supply and discharge of hydraulic pressure to and from the hydraulic chamber in the primary pulley and the hydraulic chamber in the secondary pulley are controlled by an electrically controlled supply valve and discharge valve. It is configured.

European Patent No. 0985855 International Publication No. 2010/021218

  In the inventions described in Patent Document 1 and Patent Document 2 described above, since an accumulator is provided as a hydraulic pressure source, the hydraulic pressure can be ensured even when the hydraulic pump is stopped. Since the valves for controlling the supply and discharge of the hydraulic pressure to and from the hydraulic chamber are of the type that closes in the off state when the energization is stopped, all the valves are closed when the energization is stopped due to an electrical failure. Therefore, if such a failure occurs during traveling, the transmission ratio and torque transmission state are maintained in the state immediately before the occurrence of the failure, and if the traveling state is steady, the transmission ratio is a high-speed transmission ratio (small). The gear ratio may be maintained, and climbing may not be possible or it may be difficult to re-start once stopped.

  On the other hand, a so-called normally open type valve that opens in an off state can be adopted as the supply valve and the exhaust pressure valve described above. However, in such a configuration, if the power supply is stopped, all valves are opened and the hydraulic pressure is lowered. Therefore, the torque capacity of the belt-type continuously variable transmission, the clutch, etc. is lost and the vehicle cannot travel.

  Therefore, in order to avoid such a situation, a so-called normally open type electromagnetic valve that opens in the off state is adopted for the supply valve, whereas in contrast, the exhaust valve is in the off state. It is conceivable to employ a so-called normally closed solenoid valve that closes. With this configuration, the hydraulic pressure stored in the accumulator is supplied to belt-type continuously variable transmissions, clutches, etc. when an electrical failure such as disconnection occurs or when the vehicle main switch is turned off. The torque capacity can be set to a high state. Therefore, even when an electrical failure occurs, so-called limp home travel is possible, and re-starting is possible after being temporarily stopped.

  However, since the hydraulic pressure stored in the accumulator is generally the highest hydraulic pressure required by the automatic transmission or higher, the supply valve is a normally open type and the exhaust pressure valve. Is normally closed type, for example, the main switch is turned off to stop energization, and at the same time, high pressure oil pressure is supplied to each hydraulic chamber or actuator. For this reason, for example, in a belt-type continuously variable transmission, high pressure hydraulic oil is supplied to the hydraulic chamber of a pulley that is controlled to set a gear ratio, and an upshift occurs. There is a possibility that high-pressure hydraulic pressure is supplied to a clutch or the like whose hydraulic pressure is lower than that of the stage transmission, and the durability of the hydraulic system related to the clutch is lowered.

  The present invention has been made paying attention to the above technical problem, and is directed to an automatic transmission that includes an accumulator as a hydraulic pressure source and is configured to electrically control the hydraulic pressure of an actuator. It is an object of the present invention to provide a hydraulic control device that can secure a necessary hydraulic pressure when a failure occurs and can prevent or suppress an excessive hydraulic pressure from acting on an actuator.

  In order to solve the above-mentioned problems, the invention of claim 1 is directed to a hydraulic pressure control apparatus for an automatic transmission in which a hydraulic pressure is supplied from a hydraulic power source including an accumulator to set a gear ratio and a transmission torque capacity. An actuator that sets a transmission gear ratio or a transmission torque capacity according to the pressure, and a normally open type supply electromagnetic that controls a hydraulic pressure supplied to the actuator from the accumulator and is opened when energization is stopped. A valve, a normally closed type exhaust pressure solenoid valve that controls the hydraulic pressure of the actuator by discharging the hydraulic pressure from the actuator, and that is closed when energization is stopped, and the supply solenoid valve and the exhaust pressure When the operation to stop energization of the solenoid valve is executed, the supply solenoid valve and the exhaust pressure solenoid valve are controlled to be opened. The exhaust pressure control means, and the exhaust pressure control means controls the supply solenoid valve and the exhaust solenoid valve to be in an open state, and the hydraulic pressure of the accumulator is reduced to a predetermined pressure. And a closing control means for closing the valve.

  According to a second aspect of the present invention, in the first aspect of the invention, the automatic transmission includes a first actuator to which hydraulic pressure is supplied from the accumulator and changes a groove width according to the hydraulic pressure supplied to the first actuator. And a second pulley that has a second actuator to which hydraulic pressure is supplied from the accumulator and generates a belt clamping pressure in accordance with the hydraulic pressure supplied to the second actuator, and the first pulley and the second pulley. And a belt type continuously variable transmission including a belt for transmitting torque, wherein the supply solenoid valve is disposed between the second actuator and the accumulator. The exhaust pressure solenoid valve includes a second exhaust pressure solenoid valve for discharging the hydraulic pressure of the second actuator to a drain location; A first supply solenoid valve disposed between the first actuator and the accumulator, and a first exhaust solenoid valve for discharging the hydraulic pressure of the first actuator to a drain location, the exhaust pressure control means Controls the first supply solenoid valve to be closed when an operation to stop energization of each solenoid valve is performed, and controls the second supply solenoid valve, the first exhaust pressure solenoid valve, and the second exhaust solenoid valve. Means for controlling the pressure solenoid valve to be in an open state, wherein the closing control means controls the first exhaust pressure solenoid valve and the second exhaust pressure solenoid valve to be in a closed state, and in addition, controls the first supply solenoid valve. A hydraulic control device for an automatic transmission including means for controlling a valve to an open state.

  According to a third aspect of the present invention, in the first aspect of the invention, the actuator includes a high pressure side actuator that operates while being controlled to a relatively high hydraulic pressure, and a low pressure side actuator that operates while being controlled to a relatively low hydraulic pressure. And the predetermined pressure is a pressure set based on a hydraulic pressure that can be supplied to the low-pressure side actuator.

  According to a fourth aspect of the present invention, in the second aspect of the invention, the automatic transmission is engaged with a lower hydraulic pressure than the belt-type continuously variable transmission to transmit torque, and the friction engagement device. A third actuator provided in the combined device, wherein the supply electromagnetic valve further includes a third supply electromagnetic valve provided between the third actuator and the accumulator, and the exhaust pressure electromagnetic valve The valve further includes a third exhaust pressure electromagnetic valve that discharges the hydraulic pressure of the third actuator to the drain location, and the exhaust pressure control means is configured to perform the operation when the operation of stopping energization of each electromagnetic valve is performed. The first supply solenoid valve is controlled to be in a closed state, and the third exhaust pressure solenoid valve is controlled to be opened in addition to the second supply solenoid valve, the first exhaust pressure solenoid valve, and the second exhaust pressure solenoid valve. Means for closing The control means includes the means for controlling the third exhaust pressure solenoid valve in a closed state in addition to the first exhaust pressure solenoid valve and the second exhaust pressure solenoid valve and controlling the first supply solenoid valve in an open state. This is a hydraulic control device for an automatic transmission.

  According to a fifth aspect of the invention, in the invention of the fourth aspect, the predetermined pressure is a pressure set based on a hydraulic pressure that can be supplied to the third actuator. It is a control device.

  According to the first aspect of the present invention, the supply solenoid valve is opened when energization is stopped, and the exhaust pressure solenoid valve is closed when energization is stopped. In this case, first, control for opening the supply control valve and the exhaust pressure solenoid valve is executed. Therefore, the hydraulic pressure is supplied from the accumulator to the actuator via the supply control valve, but since the actuator communicates with the drain location via the exhaust pressure solenoid valve, the hydraulic pressure of the accumulator is eventually discharged to the drain location, Accumulator hydraulic pressure decreases. When the pressure of the accumulator is reduced to a predetermined pressure, the exhaust pressure solenoid valve is controlled to be closed by stopping energization of the exhaust pressure solenoid valve, and the exhaust pressure from the actuator is stopped. That is, the hydraulic pressure of the actuator whose pressure has been reduced is supplied to the actuator and maintained in the supplied state. That is, it becomes a closed state. Therefore, when energizing each solenoid valve, even if the hydraulic pressure is finally confined, the hydraulic pressure of the accumulator is lowered prior to that, so that excessively high hydraulic pressure acts on the actuator is avoided or suppressed. be able to.

  According to the invention of claim 2, when an operation to stop energization is performed, after the hydraulic pressure of the accumulator is reduced, each solenoid valve for exhaust pressure is controlled to be closed and each solenoid valve for supply is controlled to be open. Then, since it is in a so-called closed state, it prevents or suppresses high pressure from acting on the actuator of the first pulley that sets the gear ratio, and accompanying this, the gear shifting action to the upshift side. Can do. In particular, the first supply solenoid valve that controls the hydraulic pressure supplied to the actuator of the first pulley is first controlled to the closed state, and then the hydraulic pressure of the accumulator is controlled to the open state. It is possible to reliably avoid high hydraulic pressure acting on the actuator of the first pulley.

  According to the invention of claim 3, in addition to obtaining the same effect as that of the invention of claim 1, the hydraulic pressure of the accumulator in the so-called closed state is the hydraulic pressure that can be supplied to the low-pressure side actuator. Therefore, it is possible to prevent or suppress an excessively high hydraulic pressure from acting on the low-pressure side actuator and a decrease in durability associated therewith.

  According to the invention of claim 4, in addition to obtaining the same effect as the invention of claim 2 above, in addition to the belt-type continuously variable transmission, when the operation to stop energization is performed, the friction The engagement device can be maintained in a state where torque can be transmitted. According to the fifth aspect of the present invention, it is possible to avoid or suppress the high pressure acting on the third actuator on the low pressure side from acting on the belt-type continuously variable transmission to improve its durability. it can.

It is a flowchart for demonstrating an example of the control performed with the hydraulic control apparatus which concerns on this invention. It is a flowchart for demonstrating the other example of the control performed with the hydraulic control apparatus which concerns on this invention. It is a schematic diagram which shows an example of the automatic transmission which can be made into object by this invention. It is a schematic diagram which shows an example of the hydraulic control apparatus which concerns on this invention.

  Next, the present invention will be specifically described with reference to the drawings. The present invention can be applied to a hydraulic control device for a vehicle automatic transmission such as a continuously variable transmission or a stepped transmission, and includes a belt type continuously variable transmission as an example of the automatic transmission. An example is shown schematically in FIG. The driving force source 1 may be an internal combustion engine such as a gasoline engine, an electric motor, or a so-called hybrid type combining these internal combustion engines and an electric motor. In the following description, an example in which an engine is used as the driving force source 1 will be described. Therefore, the driving force source 1 is referred to as the engine 1.

  A torque converter 2 is connected to the output side of the engine 1. This torque converter 2 has a general structure widely used in vehicles, and includes a direct coupling clutch (lock-up clutch) 3 that directly connects an input side element and an output side element. A forward / reverse switching mechanism 4 is arranged following the torque converter 2. In short, the forward / reverse switching mechanism 4 may be of any configuration as long as it can output the input torque as it is and can output the torque by reversing the direction of the torque. The example shown in FIG. Then, it is mainly composed of a double pinion type planetary gear mechanism. That is, a ring gear 6 that is an internal gear is arranged concentrically with the sun gear 5 connected to the output element of the torque converter 2, and the pinion gear meshed with the sun gear 5 is between the sun gear 5 and the ring gear 6. 7 and another pinion gear 8 meshing with the pinion gear 7 and the ring gear 6 are arranged, and these pinion gears 7 and 8 are held by the carrier 9 so that they can rotate and revolve.

  A clutch C1 is provided for setting a forward state in which the torque input to the sun gear 5 is output as it is. The clutch C1 is essentially a clutch configured to connect any two elements in the above-described double pinion type planetary gear mechanism and rotate the entire planetary gear mechanism integrally, as shown in FIG. In the example, the sun gear 5 and the carrier 9 are selectively connected. Specifically, the clutch C1 can be constituted by a wet multi-plate clutch, and therefore, a plurality of friction plates and plates and hydraulic chambers (or hydraulic actuators) (not shown respectively) for bringing them into close contact with each other. It has.

  A brake B1 is provided for setting a reverse state in which the direction of the torque input to the sun gear 5 is reversed and output. In the example shown in FIG. 3, the brake B <b> 1 is configured to selectively connect the ring gear 6 to a fixed portion 10 such as a casing and apply a reaction force to the ring gear 6 to stop its rotation. The brake B1 can be specifically a wet multi-plate type, and therefore, a plurality of friction plates and plates and hydraulic chambers (or hydraulic actuators) for bringing them into close contact with each other (not shown). And. Therefore, in the example shown in FIG. 3, the sun gear 5 is an input element, the ring gear 6 is a reaction element, and the carrier 9 is an output element, and the clutch C1 is engaged and the sun gear 5 and the carrier 9 are connected. As a result, the entire planetary gear mechanism rotates as a unit, the torque input from the sun gear 5 and the carrier 9 is output as it is, and the forward state is set. In addition, the ring gear 6 is fixed by engaging the brake B1 instead of the clutch C1, and as a result, the carrier 9 rotates in the opposite direction with respect to the sun gear 5, so that the torque acting in the opposite direction to the input torque. Is output and the reverse state is set. The clutch C1 and the brake B1 correspond to the friction engagement device according to the present invention.

  A belt type continuously variable transmission 11 is connected to the output side of the forward / reverse switching mechanism 4. The belt-type continuously variable transmission 11 has a configuration that is widely known in the past, and includes a pair of pulleys 12 and 13 each composed of a fixed sheave and a movable sheave disposed opposite thereto. A belt 14 is wound around a so-called V groove formed by a fixed sheave and a movable sheave. One pulley 12 is a driving pulley (primary pulley), and this primary pulley 12 is connected to the carrier 9 in the forward / reverse switching mechanism 4 described above. Further, a hydraulic chamber (actuator) 15 is provided on the back side of the movable sheave in the primary pulley 12, and the width of the V-groove is increased by increasing the hydraulic pressure supplied to the hydraulic chamber 15 or increasing the amount of pressurized oil. The belt 14 is configured to be narrower and increase the winding radius of the belt 14. That is, the example shown in FIG. 3 is configured to change the gear ratio by controlling the hydraulic pressure or the amount of pressure oil of the primary pulley 12.

  The other pulley 13 is a driven pulley (secondary pulley), and a hydraulic chamber (actuator) 16 is provided on the back side of the movable sheave. The belt 14 is driven by the hydraulic pressure supplied to and discharged from the hydraulic chamber 16. And a clamping pressure for setting a predetermined transmission torque capacity is generated. An output gear 18 provided on the pulley shaft 17 of the secondary pulley 13 meshes with a counter driven gear 19, and a counter drive gear 20 that rotates integrally with the counter driven gear 19 constitutes a differential that forms a final reduction gear. It meshes with the ring gear 22 of the gear 21 and is configured to transmit torque from the differential gear 21 to left and right drive wheels (not shown).

  In addition, the movement limit position of each movable sheave in each pulley 12 and 13 is prescribed | regulated by the mechanical structure. That is, when the movable sheave in the primary pulley 12 is closest to the fixed sheave, a part of the movable sheave is hooked on a portion integral with the fixed sheave so that the movable sheave does not approach the fixed sheave any more. That is, when the movable sheave is closest to the fixed sheave, the load that presses the movable sheave toward the fixed sheave is received at the engagement position between the two and the belt 14 is not further pinched. Such a structure is also used for the movable sheave and the fixed sheave in the secondary pulley 13, and in a state where the groove width of the secondary pulley 13 is reduced so that the transmission ratio is maximized, the movable sheave is fixed or The movable sheave is prevented from approaching the fixed sheave any more by being hooked on a part integral with the pulley shaft. Therefore, in this state, the belt clamping pressure that presses the movable sheave toward the fixed sheave does not increase further. Further, when the movable sheave in the primary pulley 12 is farthest from the fixed sheave, or the movable sheave in the secondary pulley 13 is farthest from the fixed sheave, the movable sheave contacts the fixed sheave or the integral part of the pulley shaft. It is configured not to move further backward in contact. Therefore, in that state, the load in the direction separating the movable sheave from the fixed sheave is received by the constituent members other than the belt 14.

  The lockup clutch 3, the clutch C 1, the brake B 1, the continuously variable transmission 11, and the like are configured to be controlled by hydraulic pressure, and a hydraulic control device 23 is provided for the control. The hydraulic control device 23 includes a plurality of electrically controlled valves, and engages the lock-up clutch 13, the clutch C 1, or the brake B 1 with hydraulic pressure that is output according to the on / off state of these valves. The gear ratio set by the continuously variable transmission 11 is changed, or the belt clamping pressure is changed to high or low. The specific configuration will be described later.

  Further, an electronic control unit (ECU) 24 is provided for controlling the gear ratio and the belt clamping pressure, and controlling the supply and discharge of the hydraulic pressure with respect to the clutch C1 and the brake B1. The electronic control unit 24 is mainly composed of a microcomputer, and is configured to perform a calculation based on input data or data stored in advance and output a control command signal. Further, the electronic control unit 24 is configured to control the output of the engine 1, and accordingly, a control command signal is output from the electronic control unit 24 to the hydraulic control unit 23 and the engine 1 described above. Has been.

  The hydraulic control device 23 according to the present invention for the automatic transmission described above is provided with a supply solenoid valve and a discharge pressure solenoid valve for each of the hydraulic chamber 15 in the primary pulley 12 and the hydraulic chamber 16 in the secondary pulley 13. Further, a solenoid valve for supply and a solenoid valve for exhaust pressure are provided for the clutch C1 and the brake B1 described above, and these solenoid valves are electrically controlled to be opened and closed to control the transmission ratio and the transmission torque capacity. Yes. An example of this is schematically shown in FIG. The hydraulic control device 23 shown here has an electric oil pump 27 that is driven by an electric motor 25 to pump up oil from an oil pan 26 and discharge it. An accumulator 28 is connected to the discharge port of the electric oil pump 27. The accumulator 28 functions as a so-called hydraulic source that stores the hydraulic pressure discharged by the electric oil pump 27 and maintains a predetermined hydraulic pressure even when the electric oil pump 27 is stopped. The maximum hydraulic pressure required for the belt type continuously variable transmission 11 described above or higher than that. A hydraulic pressure sensor 29 that detects the hydraulic pressure in the accumulator 28 is provided.

  The hydraulic pressure generated by the electric oil pump 27 or the accumulator 28 is supplied to the continuously variable transmission 11, the clutch C 1, or the brake B 1 through the oil passage 30. More specifically, a supply electromagnetic valve SLP1 is provided in an oil passage 31 that communicates the electric oil pump 27 and the accumulator 28 with the hydraulic chamber 15 in the primary pulley 12 described above, and this supply electromagnetic valve SLP1. Thus, the oil passage 31 is opened and closed to selectively supply pressure oil to the hydraulic chamber 15 in the primary pulley 12. In addition, the hydraulic chamber 15 in the primary pulley 12 is connected to an exhaust pressure electromagnetic valve SLP2 that discharges the hydraulic pressure of the hydraulic chamber 15 to a drain location such as an oil pan 26. In the example shown in FIG. 4, the exhaust pressure solenoid valve SLP <b> 2 is connected to the oil passage 31 between the supply solenoid valve SLP <b> 1 and the hydraulic chamber 15. Furthermore, a hydraulic sensor 32 that detects the pressure in the hydraulic chamber 15 and outputs a signal is provided.

  The supply solenoid valve SLP1 and the exhaust pressure solenoid valve SLP2 are valves that are electrically controlled to open and close the ports, and in the closed state, the so-called poppet type that closes the ports with almost no hydraulic leakage. It is constituted by a valve. The supply solenoid valve SLP1 is closed so that the port is closed when energized, and the valve is opened when the power is cut off (normally open type). It is comprised by the valve. On the other hand, the solenoid valve for exhaust pressure SLP2 is a so-called normally closed type (normally closed) that opens the port when energized and opens, and closes the port when energized. Type) valve. This is because even when the energization is interrupted, the hydraulic pressure is closed in the hydraulic chamber 15 to ensure a predetermined gear ratio and transmission torque capacity.

  The hydraulic supply / discharge mechanism for the hydraulic chamber 16 in the secondary pulley 13 that sets the belt clamping pressure is also configured similarly to the hydraulic supply / discharge mechanism for the hydraulic chamber 15 in the primary pulley 12 described above. That is, a supply electromagnetic valve SLS1 is provided in an oil passage 33 that communicates the electric oil pump 27 and the accumulator 28 with the hydraulic chamber 16 in the secondary pulley 13 described above, and the oil passage 33 is provided by the supply electromagnetic valve SLS1. The hydraulic pressure supply to the hydraulic chamber 16 in the secondary pulley 13 is selectively performed by opening and closing. The hydraulic chamber 16 in the secondary pulley 13 is in communication with a solenoid valve SLS2 for exhaust pressure that discharges the hydraulic pressure in the hydraulic chamber 16 to a drain location such as the oil pan 26. In the example shown in FIG. 4, the exhaust pressure solenoid valve SLS <b> 2 is connected to the oil passage 33 between the supply solenoid valve SLS <b> 1 and the hydraulic chamber 16. Further, a hydraulic sensor 34 that detects the pressure in the hydraulic chamber 16 and outputs a signal is provided.

  The solenoid valve SLS1 for supply and the solenoid valve SLS2 for exhaust pressure are valves that are electrically controlled to open and close the ports. In the closed state, the so-called poppet type that closes the ports with almost no hydraulic leakage. It is constituted by a valve. In addition, the supply solenoid valve SLS1 is closed so that the port is closed when energized, and the port is opened when the power is interrupted (normally open type). It is comprised by the valve. On the other hand, the solenoid valve for exhaust pressure SLS2 is a so-called normally closed type (normally closed) that opens the port when energized and opens, and closes the port when energized. Type) valve. This is because the hydraulic pressure is closed in the hydraulic chamber 16 to ensure a predetermined gear ratio and transmission torque capacity even when the energization is interrupted.

  Further, a supply electromagnetic valve SLC1 is provided in an oil passage 35 for supplying hydraulic pressure from the electric oil pump 27 or the accumulator 28 to the clutch C1 and the brake B1, and the oil passage 35 is opened and closed by the supply electromagnetic valve SLC1. The hydraulic pressure is selectively supplied to the hydraulic chamber in the clutch C1 and the brake B1. Further, a hydraulic pressure sensor 36 that detects a supply pressure to the clutch C1 and the brake B1 and outputs a signal is provided on the output side (discharge port side) of the supply electromagnetic valve SLC1. Further, a manual valve 37 is provided for switching the hydraulic pressure discharged from the supply electromagnetic valve SLC1 to the clutch C1 and the brake B1 and shutting off the hydraulic pressure supply. The manual valve 37 is a valve that is linked to a shift lever (not shown) provided in the driver's seat of the vehicle on which the automatic transmission described above is mounted. This is a valve that switches to supply the hydraulic pressure to the clutch C1 by setting to the forward travel position, and switches to supply the hydraulic pressure to the brake B1 instead of the clutch C1 by setting to the reverse position.

  An exhaust pressure solenoid valve SLC2 is connected to the input port (port through which the oil passage 36 is communicated) of the manual valve 37. The exhaust pressure electromagnetic valve SLC2 is a valve for discharging the pressure from the clutch C1 or the brake B1 communicated with the oil passage 35 to the drain location by the manual valve 37.

  These supply solenoid valve SLC1 and exhaust pressure solenoid valve SLC2 are valves that are electrically controlled to open and close the ports, and are so-called poppet types that close the ports with almost no hydraulic leakage in the closed state. It is constituted by a valve. The supply solenoid valve SLC1 is a so-called normally open type (normally open type) that closes the port when energized and closes the valve, and opens the port when the energization is interrupted to open the port. It is comprised by the valve. On the other hand, the solenoid valve for exhaust pressure SLC2 is a so-called normally closed type (normally closed) that opens the port when energized and opens, and closes the port when energized. Type) valve. This is to ensure a predetermined transmission torque capacity by closing the hydraulic pressure in the clutch C1 or the brake B1 even when the energization is interrupted.

  Next, the basic operation of the automatic transmission and the hydraulic control device 23 will be described. When the engine 1 is driven by turning on a main switch or a push button type engine switch (not shown), the torque output from the engine 1 is transmitted to the forward / reverse switching mechanism 4 via the torque converter 2. Is done. On the other hand, if the neutral position is selected by the shift lever, no hydraulic pressure is supplied to either the clutch C1 or the brake B1, so that they are released and torque is not transmitted to the continuously variable transmission 11 or the drive wheels. On the other hand, when the forward travel position is selected, the manual valve 37 causes the clutch C1 to communicate with the oil passage 35. In this state, the hydraulic pressure generated by the electric oil pump 27 or the hydraulic pressure of the accumulator 28 is regulated by the supply electromagnetic valve SLC1 and supplied to the clutch C1, which is engaged. That is, it will be in a forward state. When the hydraulic pressure of the clutch C1 is higher than the target hydraulic pressure, the exhaust pressure electromagnetic valve SLC2 is opened and the hydraulic pressure is reduced. Such control of the hydraulic pressure for the clutch C1 is similarly executed for the hydraulic pressure of the brake B1 when the reverse state is selected.

  On the other hand, the speed ratio is determined based on the vehicle speed, the accelerator opening, and the like, and the hydraulic pressure in the hydraulic chamber 15 in the primary pulley 12 is controlled so as to achieve the target speed ratio. That is, the supply solenoid valve SLP1 is controlled to be opened and hydraulic pressure is supplied from the electric oil pump 27 or the accumulator 28 to the hydraulic chamber 15 in the primary pulley 12, or the exhaust pressure solenoid valve SLP2 is controlled to be opened and the hydraulic chamber in the primary pulley 12 is opened. The target gear ratio is achieved by exhausting pressure from 15. The gear ratio control can be executed by a feedback control based on a deviation between the actual gear ratio and the target gear ratio after obtaining the actual gear ratio based on the rotation speed of the primary pulley 12 and the secondary pulley 13 or the like.

  Further, the transmission torque capacity in the continuously variable transmission 11 is set to a capacity capable of transmitting the driving torque according to the accelerator opening, which is to obtain the target clamping pressure based on the accelerator opening or the throttle opening of the engine 1. This is performed by controlling the supply electromagnetic valve SLS1 and the exhaust pressure electromagnetic valve SLS2 so that the hydraulic pressure of the hydraulic chamber 16 in the secondary pulley 13 becomes a hydraulic pressure corresponding to the target clamping pressure. That is, when the transmission torque capacity is increased, the supply solenoid valve SLS1 is controlled to open, and hydraulic pressure is supplied from the electric oil pump 27 or the accumulator 28 to the hydraulic chamber 16 in the secondary pulley 13, and conversely, the hydraulic chamber 16 When the hydraulic pressure is too high, the exhaust pressure electromagnetic valve SLS2 is controlled to open and exhausted from the hydraulic chamber 16 in the secondary pulley 13 to reduce the clamping pressure.

  Since the continuously variable transmission 11 transmits all of the input torque, the hydraulic pressure in each of the hydraulic chambers 15 and 16 is set to a high pressure corresponding to the torque. On the other hand, since the clutch C1 and the brake B1 described above do not handle all of the torque that should be transmitted from the engine 1 to the drive wheels, the transmission torque capacity or hydraulic pressure is lower than the hydraulic pressure in the continuously variable transmission 11. It's okay.

  By the way, as described above, each of the solenoid valves SLP1, SLS1, SLC1 for supply is a so-called normally open type valve, and therefore, when energized, the solenoid valves SLP1, SLS1, SLC1 are closed. This is done by energizing SLS1 and SLC1. On the other hand, each solenoid valve SLP2, SLS2, SLC2 for exhaust pressure is a so-called normally closed type valve, and is opened when energized. Therefore, the exhaust pressure is applied to these solenoid valves SLP2, SLS2, SLC2. This is done by energizing. The solenoid valves SLP1, SLS1, SLC1, SLP2, SLS2, and SLC2 are configured and combined in this manner because the accumulator 28 is not hydraulic when there is a situation where it cannot be energized due to disconnection or failure of the electronic control unit 24. This is because at least limp home travel is enabled by supplying the gear to the step transmission 11, the clutch C1, or the brake B1. More specifically, when the solenoid valves SLP1, SLS1, and SLC1 for supply are in a so-called off state because they cannot be energized, the solenoid valves SLP1, SLS1, and SLC1 are opened, and are used for exhaust pressure. The solenoid valves SLP2, SLS2, and SLC2 are closed when they are not energized. Therefore, the hydraulic pressure is confined in the hydraulic chambers 15 and 16 of the continuously variable transmission 11 and the hydraulic chambers of the clutch C1 or the brake B1, and a predetermined transmission torque capacity or speed ratio is maintained.

  The hydraulic control apparatus according to the present invention turns off the solenoid valves SLP1, SLS1, SLC1, SLP2, SLS2, and SLC2 when the power supply is artificially stopped, for example, by turning off the main switch or engine switch of the vehicle. Prior to this, the following control is executed. FIG. 1 is a flowchart for explaining an example of the control, and this routine is repeatedly executed every predetermined short time. First, it is determined whether or not there has been an instruction to stop the engine 1 by the driver (step S1). This may be determined based on a signal output by turning off a key switch or a push-type engine switch provided in the vehicle. If a negative determination is made in step S1, the process returns without performing any particular control, and the routine of FIG.

  On the other hand, if there is an engine stop instruction to stop energization and an affirmative determination is made in step S1, first, the supply solenoid valve (SOL) SLS1 and the exhaust pressure solenoid for the secondary pulley 13 are used. The valve (SOL) SLS2 is controlled to open (step S2). Since the supply solenoid valve SLS1 is a so-called normally open type valve, the energization is cut off. On the other hand, the exhaust pressure solenoid valve SLS2 is a so-called normally closed type valve. Will continue. Therefore, the accumulator 28 is communicated with the drain location via these solenoid valves SLS1 and SLS2, and the hydraulic pressure is discharged from the accumulator 28. In addition to such control, the supply solenoid valve SLP1 for the primary pulley 12 and the supply solenoid valve (SOL) SLC1 for the clutch C1 or the brake B1 are controlled to be closed, and the respective exhaust pressure solenoids. The valves (SOL) SLS2 and SLC2 are controlled to be opened. Since the operation of stopping the engine 1 is normally performed in a state where the vehicle is stopped, the pressure ratio is set to the maximum start gear ratio by exhausting the pressure from the hydraulic chamber 15 in the primary pulley 12, Further, the neutral state is set by releasing the clutch C1 or the brake B1 so that the torque does not appear on the drive wheels.

  Since the hydraulic pressure of the accumulator 28 is reduced by executing the control in step S2, it is determined whether or not the hydraulic pressure has become equal to or lower than a predetermined pressure (step S3). The pressure used as a criterion for the determination is a pressure at which the hydraulic pressure of the accumulator 28 is allowed in a so-called low pressure system such as the clutch C1, for example, a pressure that does not cause an abnormality in the hydraulic sensor 36. It can be predetermined based on this. Further, the determination of the hydraulic pressure of the accumulator 28 can be made based on the pressure detected by the hydraulic sensor 29 described above. If the negative pressure is determined in step S3 because the hydraulic pressure of the accumulator 28 is still high, the control in step S2 described above is continued. On the other hand, when the hydraulic pressure of the accumulator 28 is sufficiently lowered and the determination in step S3 is affirmative, the engine 1 is stopped and the energization of each solenoid valve SLP1, SLS1, SLC1, SLP2, SLS2, SLC2 is performed. Is stopped (step S4).

  Accordingly, the solenoid valves SLP1, SLS1, and SLC1 for supply are opened, and the solenoid valves SLP2, SLS2, and SLC2 for exhaust pressure are closed. That is, the hydraulic pressure of the accumulator 28 is supplied to the hydraulic chambers 15 and 16 and the clutch C1 or the brake B1 of the continuously variable transmission 11 to be confined. However, since the hydraulic pressure is sufficiently lowered, the pressure in each hydraulic chamber does not become excessively high, and the situation that the durability is not impaired does not occur. For example, since the hydraulic pressure supplied to the hydraulic chamber 15 in the primary pulley 12 is sufficiently low, there is no effect of upshifting when the primary pulley 12 is not rotating, and slippage between the pulleys 12 and 13 and the belt 14 or the cause thereof. Wear and the like can be avoided. Further, in the low-pressure system, excessively high hydraulic pressure does not act, so that damage to the oil passage 35 and the hydraulic sensor 36 can be avoided in advance. Note that, when the power supply is stopped due to disconnection or the like during traveling, high hydraulic pressure is confined in the hydraulic chambers 15 and 16 of the continuously variable transmission 11, the clutch C1, or the brake B1, so that the transmission ratio and the transmission torque capacity are ensured. Thus, so-called limp home driving becomes possible.

  Note that the hydraulic pressure stored in the accumulator 28 is a hydraulic pressure required for the continuously variable transmission 11 and may be considerably high. Therefore, when the exhaust pressure electromagnetic valve SLS2 for the secondary pulley 13 is opened, the oil hammer is applied. There is a possibility that What is necessary is just to comprise so that control shown in FIG. 2, for example may be performed in order to suppress such an oil hammer. The control example shown in FIG. 2 is an example in which the opening control of the supply electromagnetic valve SLS1 for the secondary pulley 13 is gradually performed in the control shown in FIG. 1 described above. Specifically, step S2 described above is used. Subsequent to this control, control (step S2-1) for gradually opening the supply electromagnetic valve SLS1 for the secondary pulley 13 is executed. Since the other steps in the routine shown in FIG. 2 are the same as those in FIG. 1, the same step numbers as those in FIG. Therefore, if the control shown in FIG. 2 is configured to execute, even if the supply solenoid valve SLS1 for the secondary pulley 13 opens and the hydraulic pressure of the accumulator 28 acts on the hydraulic chamber 16 in the secondary pulley 13, Since the oil pressure gradually increases, it is possible to prevent the oil hammer from occurring or to reduce the oil hammer.

  Since the control described above is executed by the driver performing an operation to stop energization, the vehicle is stopped, and the continuously variable transmission 11 has the lowest gear ratio (the largest gear ratio). Is set. Therefore, the movable sheave in the primary pulley 12 is moved to the limit position and away from the fixed sheave, and the movement is prevented by the movable sheave being caught by a component such as a pulley shaft, and thus the movable sheave is further retracted. Even if a load is generated in a direction, the load is received by a mechanical component. Similarly, the movable sheave in the secondary pulley 13 is closest to the fixed sheave, and the load in the approaching direction is received by the fixed sheave or the pulley shaft, and therefore, an excessive clamping pressure does not act on the belt 14.

  The specific example of the present invention has been described above. However, the present invention is not limited to the above specific example, and can be applied to a hydraulic control device for an automatic transmission other than a belt-type continuously variable transmission. The main point of the present invention is that the accumulator as a hydraulic pressure source is controlled to be closed by controlling energization so that the supply and exhaust solenoid valves are opened and closed as described above to reduce the accumulator hydraulic pressure. What is necessary is just to be comprised so that it may be controlled to a closed state after making it. When a belt type continuously variable transmission is a target, a pulley for setting a gear ratio may be a driven pulley instead of a driving side, and a pulley for setting a clamping pressure may be a driving pulley.

  DESCRIPTION OF SYMBOLS 4 ... Forward / reverse switching mechanism, C1 ... Clutch, B1 ... Brake, 11 ... Belt type continuously variable transmission, 12, 13 ... Pulley, 14 ... Belt, 15, 16 ... Hydraulic chamber (actuator), 23 ... Hydraulic control device, 24 ... Electronic control unit 28 ... Accumulator 29, 32, 34, 36 ... Hydraulic sensor, 30, 31, 33, 35 ... Oil passage, SLP1, SLS1, SLC1 ... Supply solenoid valve, SLP2, SLS2, SLC2 ... Exhaust Pressure solenoid valve.

Claims (5)

In a hydraulic control device for an automatic transmission in which hydraulic pressure is supplied from a hydraulic power source including an accumulator and a transmission ratio and a transmission torque capacity are set,
An actuator for setting a gear ratio or transmission torque capacity according to the supplied hydraulic pressure;
A normally open type supply solenoid valve that controls the hydraulic pressure supplied to the actuator from the accumulator and is in a valve-opened state by stopping energization;
Controlling the hydraulic pressure of the actuator by discharging the hydraulic pressure from the actuator, and a normally closed type exhaust pressure electromagnetic valve that is in a closed state by stopping energization;
An exhaust pressure control means for controlling the supply solenoid valve and the exhaust pressure solenoid valve to an open state when an operation to stop energization of the supply solenoid valve and the exhaust pressure solenoid valve is performed;
Closed control means for closing the exhaust pressure electromagnetic valve based on the fact that the supply solenoid valve and the exhaust pressure solenoid valve are controlled to be opened by the exhaust pressure control means and the hydraulic pressure of the accumulator is reduced to a predetermined pressure. And a hydraulic control device for an automatic transmission. The automatic transmission has a first actuator that is supplied with hydraulic pressure from the accumulator, a first pulley that changes a groove width according to the hydraulic pressure supplied to the first actuator, and hydraulic pressure that is supplied from the accumulator. A second pulley having a second actuator and generating a belt clamping pressure according to a hydraulic pressure supplied to the second actuator; and a belt that is wound around the first pulley and the second pulley to transmit torque. Belt type continuously variable transmission,
The supply solenoid valve includes a second supply solenoid valve disposed between the second actuator and the accumulator;
The solenoid valve for exhaust pressure includes a solenoid valve for second exhaust pressure that discharges the hydraulic pressure of the second actuator to a drain location,
A first supply solenoid valve disposed between the first actuator and the accumulator; and a first exhaust pressure solenoid valve for discharging the hydraulic pressure of the first actuator to a drain location;
The exhaust pressure control means controls the first supply solenoid valve to a closed state when an operation to stop energization of each solenoid valve is performed, and the second supply solenoid valve and the first exhaust pressure solenoid Means for controlling the valve and the second solenoid valve for exhaust pressure to be in an open state,
The closing control means includes means for controlling the first supply solenoid valve to an open state in addition to controlling the first exhaust pressure solenoid valve and the second exhaust pressure solenoid valve to a closed state. The hydraulic control device for an automatic transmission according to claim 1. The actuator includes a high-pressure side actuator that operates under control of a relatively high hydraulic pressure, and a low-pressure side actuator that operates under control of a relatively low hydraulic pressure,
The hydraulic control device for an automatic transmission according to claim 1, wherein the predetermined pressure is a pressure set based on a hydraulic pressure that can be supplied to the low-pressure side actuator. The automatic transmission further includes a friction engagement device that engages with a lower hydraulic pressure than the belt-type continuously variable transmission and transmits torque, and a third actuator provided in the friction engagement device. ,
The supply solenoid valve further includes a third supply solenoid valve provided between the third actuator and the accumulator,
The exhaust pressure solenoid valve further includes a third exhaust pressure solenoid valve that discharges the hydraulic pressure of the third actuator to the drain location,
The exhaust pressure control means controls the first supply solenoid valve to a closed state when an operation to stop energization of each solenoid valve is performed, and the second supply solenoid valve and the first exhaust pressure solenoid Means for controlling the third exhaust pressure solenoid valve in an open state in addition to the valve and the second exhaust pressure solenoid valve;
The closing control means controls the third exhaust pressure solenoid valve to a closed state in addition to the first exhaust pressure solenoid valve and the second exhaust pressure solenoid valve, and controls the first supply solenoid valve to an open state. The hydraulic control device for an automatic transmission according to claim 2, further comprising means.   5. The hydraulic control device for an automatic transmission according to claim 4, wherein the predetermined pressure is a pressure set based on a hydraulic pressure that can be supplied to the third actuator.

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